Ammonia as an active doping source gas of hydrogenated amorphous germanium films

Abstract

In this work the electrical properties of nitrogen-doped hydrogenated amorphous germanium films ͑a-Ge:H͒ using ammonia ͑NH 3 ͒ as a gaseous doping source are reported. The results are compared with those of N-doped a-Ge:H films using N 2 as a source gas. The doping mechanisms appear to be similar in both cases. However, the doping efficiency of NH 3 is smaller than that of N 2 . The use of NH 3 also induces a very large topological disorder. The present results give support to the view that active N doping in a-Ge:H originates from overcoordinated nitrogen atoms ͑N 4 ϩ ͒ without the need of one or more hydrogen neighbors. ͓S0163-1829͑96͒05020-5͔

Structural changes induced by nitrogen in the a-Ge:H network

“…For example, it has been argued that NH and NH 2 atomic configurations, which are expected to occur in the network due to the preferential attachment of H to N, may be an important source for the observed increased disorder. 5 The present article reports on the structural changes induced by the incorporation of nitrogen in the a-Ge:H network as monitored by infrared ͑IR͒ spectroscopy. In order to be able to detect N-H bonds by this technique, a-Ge͑N͒:H samples having nitrogen concentrations (C N ) between 2 and 6 at.…”

“…These studies have shown that, for C N Ͻ1%, N exhibits normal doping behavior, similar to other traditional dopant impurities, including augmented disorder and defect density. [3][4][5] However, the details of the structural modifications introduced by N in a-Ge:H are still an open question. For example, it has been argued that NH and NH 2 atomic configurations, which are expected to occur in the network due to the preferential attachment of H to N, may be an important source for the observed increased disorder.…”

Steady-state photoconductivity of gallium- and indium-doped hydrogenated amorphous germanium thin films

“…[2][3][4][5] As part of this research effort, n-and p-type doping studies of a-Ge:H have been undertaken by our group, using different elements of columns III and V of the Periodic Table as dopant species. [6][7][8][9][10][11][12][13] The measurement of the photoconductivity ͑PC͒ is a valuable tool to investigate the recombination processes and the distribution of deep defect states in the mobility gap of amorphous semiconductors. In particular, the dependence of the PC on the position of the Fermi level (E F ) in doped samples, provides information on the recombination processes of electrons and holes, as E F moves toward the band edges.…”

Ligas amorfas de germânio-carbono e germânio-nitrogênio hidrogenados

“…Recentemente, progressos na obtenção do germânio amorfo com qualidade eletrônica [11][12][13] têm aumentado o interesse neste material. Desta forma, têm sido desenvolvido diversos estudos sobre este material [12,[14][15][16][17][18][19][20][21][22][23].…”

“…Recentemente, progressos na obtenção do germânio amorfo com qualidade opto-eletrônica [11][12][13] têm aumentado o interesse neste material. Desta forma, múltiplos estudos estão sendo desenvolvidos, desde as propriedades a nível de dopagem [12,[14][15][16][17][18][19], utilizando tanto elementos da coluna III como da coluna V, até estudos com ligas, utilizando elementos tais como, nitrogênio, carbono e estanho [20][21][22][23].…”